Calibration method for a universal roll stand

ABSTRACT

In a calibration method for a universal roll stand with horizontal rolls and vertical rolls, wherein the horizontal rolls are supported in upper and lower horizontal chocks and the vertical rolls are supported in vertical chocks and wherein the horizontal rolls are configured to be screwed down on one another and the vertical rolls are configured to be screwed down on the horizontal rolls, the vertical chocks are moved between the horizontal chocks such that vertical roll gaps remain between the horizontal rolls and the vertical rolls. Subsequently, spacers are arranged between the vertical chocks and at least one of the upper and the lower horizontal chocks. The horizontal chocks are advanced toward one another until the horizontal chocks contact the vertical chocks or the spacers, wherein the horizontal chocks during advancing are loaded maximally with an advancing force. The horizontal chocks are loaded after completion of advancing with a calibration force which is greater than the advancing force. After loading with the calibration force, the reached positional values of the horizontal chocks are measured and reference positions for subsequent rolling processes are determined based on the reached position values.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a calibration method for a universal roll stand with horizontal rolls and vertical rolls, wherein the horizontal rolls are supported in upper and lower horizontal chocks and wherein the vertical rolls are supported in vertical chocks. The horizontal rolls can be screwed down against one another, and the vertical rolls can be a screwed down against the horizontal rolls.

[0003] 2. Description of the Related Art

[0004] Such calibration methods are known in general. For example, the patent documents DE 35 01 622 C2, EP 0 483 939 B1, and EP 0 275 875 B1 disclose such methods.

[0005] According to DE 35 01 622 C2 an axial adjustment of the horizontal rolls is performed. This document discloses moreover a method for vertical adjustment of the horizontal rolls. However, the method described herein requires that the rolls are conical.

[0006] According to the method of EP 0 483 939 B1, the horizontal rolls are aligned parallel and horizontally to one another. A method for a vertical adjustment of the horizontal rolls is not disclosed.

[0007] According to the method of EP 0 275 875 B1, the rolls are moved by an electromechanical coarse adjusting device in the universal roll stand to a roll gap zero or to a defined roll gap by means of calibration pieces. By means of a hydraulic fine adjustment, the stand and adjusting parts positioned within the horizontal as well as vertical force flux are subjected by a pressure increase in the adjusting cylinders to a compressive strain which corresponds to an average theoretical expected rolling force of the pass schedule. The precise sequence of calibration and the arrangement of the calibration pieces is not disclosed in this document.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide a calibration method for a universal roll stand with horizontal and vertical rolls in which the horizontal rolls can be positioned precisely relative to the vertical rolls independent of the shape of the rolls.

[0009] In accordance with the present invention, this is achieved by the following method steps:

[0010] the vertical chocks are moved between the horizontal chocks such that vertical roll gaps remain between the horizontal rolls and the vertical rolls;

[0011] spacer elements are arranged between the vertical chocks, on the one hand, and the upper and/or the lower horizontal chocks, on the other hand;

[0012] the horizontal chocks are advanced toward one another until they rest against the vertical chocks or the spacer elements, wherein the horizontal chocks during advancing are loaded maximally with an advancing force;

[0013] the horizontal chocks are loaded after completion of advancing with a calibration force which is greater than the advancing force; and,

[0014] after loading with the calibration force, the reached position values of the horizontal chocks are measured and reference positions are determined, based on the reached position values, for the subsequent rolling processes.

[0015] When advancing of the horizontal chocks is controlled by position control, the calibration method is especially functionally reliable.

[0016] When nominal end position values are preset in the control elements for the horizontal chocks, wherein the nominal end position values are selected such that the horizontal chocks, before reaching the nominal end position values, have contacted the vertical chocks or the spacer elements with certainty, it is always possible to perform the calibration method.

[0017] When, upon reaching the nominal end position values, the method steps that are to follow the advancement of the horizontal chocks are not performed and an error communication is issued, errors can be easily detected.

[0018] When the advancement of the horizontal chocks is carried out in two partial advancing steps and between the partial advancing steps forces are measured that occur in the non-rolling state within the control elements for the horizontal chocks, these forces are available for subsequent rolling processes as correction or offset values for loading the control elements.

[0019] It is also possible, if desired, to advance the horizontal chocks successively or simultaneously against the vertical chocks or the spacer elements.

[0020] When loading of the horizontal chocks with the calibration force is force-controlled, a force compensation can be carried out between the horizontal chocks.

[0021] When at least the horizontal chocks, preferably also the vertical chocks, are hydraulically advanceable, the universal roll stand is of an especially simple configuration.

[0022] When the calibration force is smaller than the rolling force to be exerted in the subsequent rolling processes, the spacer elements arranged between the vertical chocks and the horizontal chocks will not be damaged.

[0023] When the horizontal chocks and the vertical chocks, after measuring the position values, are moved apart by position control, the chocks can be stopped in time before reaching the movement-limiting stops.

BRIEF DESCRIPTION OF THE DRAWING

[0024] In the drawing:

[0025]FIG. 1 is a side view of the horizontal and vertical rolls of a universal roll stand; and

[0026]FIG. 2 is a flowchart of the method steps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] According to FIG. 1, a universal roll stand has horizontal rolls 1, 2 and vertical rolls 3, 4. The horizontal rolls 1, 2 are supported in horizontal chocks 5, 6, the vertical rolls 3, 4 in vertical chocks 7, 8. The chocks 5 through 8 are adjustable by control elements 9-12. The control elements 9-12 are hydraulic cylinder units. The chocks 5-8 are thus hydraulically moved.

[0028] The hydraulic cylinder units 9-12 can be moved as desired by position control or force control. By means of the control elements 9, 10 for the horizontal rolls 1, 2, the latter are movable toward one another (can be screwed down against one another). The vertical rolls 3, 4 are adjustable (can be screwed down) against the horizontal rolls 1, 2 by means of the control elements 11, 12.

[0029] The universal roll stand illustrated in FIG. 1 serves to roll a profiled section (not illustrated in FIG. 1), for example, a double T beam (I beam). The horizontal rolls 1, 2 roll the center stay of the profiled section, the vertical rolls 3, 4, in interaction with the horizontal rolls 1, 2, roll the flanges of the profiled section. For the quality of the rolled profiled section it is important, inter alia, that the stay is rolled position-precisely. It is therefore important to adjust the horizontal rolls 1, 2 vertically such that the stay is rolled centrally. This adjustment of the horizontal rolls 1, 2 relative to the vertical rolls 3, 4 is referred to as the so-called pass line. This adjustment or calibration of the pass line is the subject matter of the present invention.

[0030] The actual positions p of the hydraulic cylinder units 9, 10 are thus to be calibrated in that the functional interrelationship between the actual positions p and the position of the lower edge of the upper horizontal roll 1 or the position of the upper edge of the lower horizontal roll 2 is determined relative to the pass line.

[0031] The position of the lower edge of the upper horizontal roll 1 relative to the pass line depends on the diameter of the upper horizontal roll 1, the spacing of the roll axis of the upper horizontal roll 1 to the lower edge of the upper horizontal chock 5, and the spacing of the upper horizontal chock 5 relative to the pass line.

[0032] The diameter of the upper horizontal roll 1 can be easily measured or determined otherwise. The spacing of the roll axis of the upper horizontal roll 1 to the lower edge of the upper horizontal chock 5 is fixed. It is thus sufficient to measure it once beforehand or to know it by other means. Accordingly, only the functional interrelationship between the spacing of the lower edge of the upper horizontal chock 5 to the pass line and the actual position p of the hydraulic cylinder units 9 must be determined. This is the subject matter of the method described in the following. For evaluating the interrelationship thus determined, the position of the vertical roll center relative to the upper edge of the vertical chocks 7, 8 as well as, optionally, the thickness of the spacer elements (spacers) 16 which are arranged between the upper horizontal chock 5 and the vertical chocks 7, 8 must be known.

[0033] The functional interrelationship between the actual positions p of the hydraulic cylinder units 10 and the position of the upper edge of the lower horizontal roll 2 relative to the pass line can be determined based on analog considerations from the functional interrelationship between the spacing of the upper edge of the lower horizontal chock 6 to the pass line. In this connection, the position of the vertical roll center relative to the lower edge of the vertical chock 7, 8 as well as, optionally, the thickness of the spacers 16 arranged between the lower horizontal chock 6 and the vertical chocks 7, 8 are presumed to be known.

[0034] When these parameters are known, the horizontal rolls 1, 2 can be calibrated relative to the vertical rolls 3, 4 as described in the following in connection with FIG. 2.

[0035] First in step 13 the horizontal chocks 5, 6 are moved apart. Subsequently, in step 14, the vertical chocks 7, 8 are moved between the horizontal chocks 5, 6. The vertical chocks 7, 8 are moved only so far that vertical roll gaps v1, v2 remain between the horizontal rolls 1, 2 and the vertical rolls 3, 4. The vertical roll gaps v1, v2 must be greater than zero, at least slightly.

[0036] Subsequently, in step 15, spacers 16 are arranged between the vertical chocks 7, 8, on the one hand, and the horizontal chocks 5, 6, on the other hand. These spacers 16 have flat, smooth-surface machined contacts surfaces 16′ via which they interact with contact surfaces 5′-8′ of the chocks 5-8 also machined with a smooth surface.

[0037] Subsequently, the horizontal chocks 5, 6—simultaneously or successively—are advanced toward one another. The advancing action of the horizontal chocks 5, 6 is carried out in two partial advancing steps.

[0038] First, the control elements 9, 10 are moved to an intermediate position p1 in step 17. Subsequently, in step 18, forces F are measured which are present in the control elements 9, 10 at this time in order to determine, based thereon, correction or offset values with which the control elements 9, 10 for the horizontal chocks 5, 6 are to be loaded in order to apply in the subsequent rolling processes the desired rolling forces FW.

[0039] In the second partial advancing step, the horizontal chocks 5, 6 are then advanced farther toward one another until they rest against (contact) the vertical chocks 7, 8 or the spacers 16. For this purpose, in step 19, nominal end position values p2* are preset in the control elements 9, 10. The control elements 9, 10 are then farther advanced by position control. The control elements 9, 10 exert in this connection a—corrected—force F on the horizontal chocks 5, 6. The force F is limited to an advancing force FV. The horizontal chocks 5, 6 are thus loaded maximally by this advancing force FV during advancing. The horizontal chocks 5, 6 in the second partial advancing step can be advanced simultaneously or successively against the vertical chocks 7, 8 or against the spacers 16.

[0040] The nominal end position values p2* are selected such that the horizontal chocks 5, 6, before reaching these nominal values p2*, have with certainty been moved against the vertical chocks 7, 8 or against the spacers 16. Accordingly, in step 20, it is first checked whether the force F actually exerted by the control elements 9, 10 surpasses the advancing force FV. If this is not the case, it is checked in step 21 whether the nominal end position values p2* have been reached. Is that not the case, the method sequence returns to step 21.

[0041] When the nominal end position values p2* have been reached, this is an indication that at least one of the calibration conditions is not fulfilled. In this case an error communication is thus issued in step 22 and the further course of the calibration method is not performed.

[0042] After contact of the horizontal chocks 5, 6 on the vertical chocks 7, 8, the control elements 9, 10 are switched to force control operation and are loaded in step 23 with a calibration force FK. The calibration force FK is greater than the advancing force FV but smaller than the rolling force FW which is to be exerted in the subsequent rolling processes. Typical values for the advancing force FV are 1% to 10% of the rolling force FW, typical values of the calibration force FK are 10% to 30% of the rolling force FW.

[0043] After loading the horizontal chocks 5, 6 with the calibration force FK, the reached actual positions, respectively, the position values p of the horizontal chocks 5, 6 are measured in step 24. Based on the position values p, reference positions for the subsequent rolling processes are determined and the control elements 9, 10 are thus calibrated.

[0044] Finally, in step 25 the chocks 5-8 are moved apart by positioned control and the spacers 16 are removed.

[0045] With the method according to the invention it is possible to adjust in an automated sequence the horizontal rolls 1, 2 exactly relative to the roll center of the vertical rolls 3, 4 independent of the shape of the rolls 1 to 4.

[0046] The vertical chocks 7, 8 are, in general, of the same height and arranged at the same level. Moreover, in general, the spacer elements 16 are of identical height. With the method according to the invention, the exact adjustment of the horizontal rolls 1, 2 relative to the roll center of the vertical rolls 3, 4 at the same time also preadjusts the horizontal rolls 1, 2 horizontally and parallel to one another.

[0047] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles. 

What is claimed is:
 1. A calibration method for a universal roll stand with horizontal rolls and vertical rolls, wherein the horizontal rolls are supported in upper and lower horizontal chocks and wherein the vertical rolls are supported in vertical chocks, wherein the horizontal rolls are configured to be screwed down on one another and wherein the vertical rolls are configured to be screwed down on the horizontal rolls; the method comprising the steps: moving the vertical chocks between the horizontal chocks such that vertical roll gaps remain between the horizontal rolls and the vertical rolls; arranging spacers between the vertical chocks and at least one of the upper and the lower horizontal chocks; advancing the horizontal chocks toward one another until the horizontal chocks contact the vertical chocks or the spacers, wherein the horizontal chocks during advancing are loaded maximally with an advancing force; loading the horizontal chocks after completion of advancing with a calibration force which is greater than the advancing force; and, after loading with the calibration force, measuring the reached position values of the horizontal chocks and determining, based on the reached position values, reference positions for subsequent rolling processes.
 2. The method according to claim 1 , wherein the step of advancing the horizontal chocks is carried out by position control.
 3. The method according to claim 1 , further comprising the steps of pre-setting nominal end position values in the control elements for the horizontal chocks and selecting the nominal end position values such that the horizontal chocks, before reaching the nominal end position values, have contacted the vertical chocks or the spacers with certainty.
 4. The method according to claim 3 , further comprising the steps of preventing further method steps from being carried subsequent to the step of advancing and issuing an error communication when the nominal end position values for the horizontal chocks have been reached.
 5. The method according to claim 1 , wherein the step of advancing the horizontal chocks comprises two partial advancing steps, the method further comprising the step of measuring forces present in the control elements for the horizontal chocks between the partial advancing steps.
 6. The method according to claim 1 , wherein the horizontal chocks are advanced successively against the vertical chocks or the spacers.
 7. the method according to claim 1 , wherein the horizontal chocks are advanced simultaneously against the vertical chocks or the spacers.
 8. The method according to claim 1 , wherein loading of the horizontal chocks with the calibration force is carried out by force control.
 9. The method according to claim 1 , wherein at least the horizontal chocks are configured to be hydraulically advanced.
 10. The method according to claim 1 , wherein the vertical chocks are configured to be hydraulically advanced.
 11. The method according to claim 1 , wherein the calibration force is smaller than a rolling force to be applied in the subsequent rolling processes.
 12. The method according to claim 1 , wherein the horizontal chocks and the vertical chocks are moved apart by position control after measuring the reached position values. 